1. Field of the Invention
The present invention relates, in general, to rotating and/or orbiting buffing and/or polishing devices and in particular to centering devices for centering a back plate to a buffing and/or polishing pad.
2. Related Art
Buffing and/or polishing devices (also known as “buffers” or “polishers” are all herein referred to as “buffing devices”) are devices having a soft absorbent surface known as a buffing or polishing pad or material (herein referred to as a “buffing pad”), by which polishing material is applied, and utilized for polishing a surface using friction. Buffing devices vary in type from non-powered hand-held devices to buffing devices capable of being utilized with powered head-units (generally known as a “polisher power tool”). Buffing devices capable of being utilized with powered head-units include rotary and random orbital buffing devices.
Rotary buffing devices are buffing devices capable of having their respective buffing pads move in a rotational motion (i.e., spinning) Random orbital buffing devices are buffing devices that are capable of having their respective buffing pads move in a combined spinning and orbital motion.
One of the latest generations of known rotary and random orbital buffing devices include a buffing pad attached to a buffing device back plate as shown in FIGS. 1A through 1C. The buffing device is capable of being connected to a powered head-unit that physically connects to the back plate.
In FIG. 1A, a perspective view is shown of a buffing device back plate (simply referred to as the “back plate”) 100 separated from a buffing pad 102. The back plate 100 may have back surface 104, connection member 106, optional connection rod 108, edge 110, and front surface (not shown). The buffing pad 102 may have an outer surface 112, back surface 114, inner surface 116, and inner wall surface 118. In FIG. 1B, a perspective view is shown of the both the back plate 100 and buffing pad 102 physically connected together. Similarly, in FIG. 1C, a side view is shown of the both the back plate 100 and buffing pad 102 physically connected together along the front surface 120 of the back plate 100 and the inner surface 116 of the buffing pad 102. From FIG. 1C, it is appreciated that the edge 110 of the back plate 100 is resting against the inner surface 116 and inner wall surface 118 of the buffing pad 102 at a contact point 122.
Typically, the back surface 104 and connection member 106 of the back plate 100 are constructed of a hard material such as metal, wood, plastic, epoxy resin, polyurethane, or other rigid materials. The optional connection rod 108 may be a threaded rod made of hard material that is capable of physically engaging the buffing device powered head-unit (not shown). If no optional connection rod 108 is utilized, the connection member 106 may include a threaded shaft (not shown) within the connection member 106 that is capable of physically engaging the buffing device powered head-unit with a threaded rod.
Generally, the outer surface 112 of the buffing pad 102 are constructed of soft or semi-soft material for use in polishing a surface. The material may include foam, polyurethane, wool, or other material used for polishing surfaces. The inner surface 116 and inner wall surface 118 of the buffing pad 102 define the surfaces of a cavity 124 within the buffing pad 102. The cavity 124 generally assists in roughly centering the back plate 100 to the buffing pad 102.
Within this cavity 124, the inner surface 116 and inner wall surface 118 is generally coated with a hard material (not shown) such as plastic, epoxy resin, or polyurethane. As a result of applying the coating material on the buffing pad 102, the inner wall surface 118 may be curved inwards towards the inner surface 116 resulting in the cavity 124 having a curved-up “cup” type shape. The reason for this cup shape is that the coating process usually involves a pressure lamination molding process that would result in unwanted “hot spots” on the buffing pad 102 if the inner wall surface 118 were molded at 90 degrees from the inner surface 116.
In addition to the coating material, the inner surface 116 may include fabric hook-and-loop fasteners (also known as “hook and loop,” “burr,” and “touch” fasteners and generally identified by the registered trademark brand name VELCRO® herein referred to as “hook-and-loop fabric”) attached to the inner surface 116. As an example, the inner surface 116 have attached the loop-side of the hook-and-loop fabric and the front surface 120 have attached the hook-side of the hook-and-loop fabric. The hook-and-loop fabric may be utilized to physically attach the front surface 120 of the back plate 100 to the inner surface 116 of the buffing pad 102.
Unfortunately, these types of known rotary and random orbital buffing devices have problems relating to the difficulties in centering the front surface 120 of the back plate 100 with the inner surface 116 of the buffing pad 102. These difficulties result from the lack of an accurate centering system between the back plate 100 and buffing pad 102 and a general lack of tolerance control on the size and shape of the cavity 124.
Generally, these types of known rotary and random orbital buffing devices have backing plates 100 that have to be produced to fit the curved shaped cavity 124 of the buffing pad 102. This fit includes having the edge 110 of the back plate 102 placed sufficiently deep in the cavity 124 so as to prevent the edge 110 from slipping out of the cavity 124 and hitting an external material (not shown) to be polished. Unfortunately, this fit does not include accurate centering of the back plate 100 within the cavity 124, which typically results in unwanted vibration while in operation.
In general, spinning objects should be centered with high precision to prevent unwanted vibration because unwanted vibration causes, as an example, operator fatigue and annoyance, undesirable buffing results, premature wear of the bearings of the powered head-unit, potential damage to the buffing pad 100, and other undesirable effects. In addition, objects moving with combined rotational and orbital motion experience violent forces that can significantly amplify the problems associated with uncentered spinning objects. This motion places heavy stress on the hook-and-loop fabric holding the buffing pad 102 to the back plate 100. Typically this motion is so violent that it can shear the loops on the inner surface 116 of the buffing pad 100 and create heat that is capable of loosing the adhesives that typically attach the hook-and-loop fabric on to the buffing pad 100.
As mentioned above, the cavity 124 is capable of roughly centering the back plate 100 to the buffing pad 102 and preventing the back plate 100 from hitting any external surface (not shown) that is to be buffed. Unfortunately, as a result of the violet motion associated with an orbital buffing device, the use of a recessed soft material (such as, for example, foam) within the cavity 124 results in the edge 110 of the back plate 100 acting as cutting blade within the cavity 124. As such, the edge 110 of the back plate 100 will eventually cut into the inner wall surface 118 at the contact point 122 and destroy the buffing pad 102 prematurely.
Therefore, there is a need for system capable of solving the above described problems with known buffing pads.